Teachers can also join your classes but as students, all you need to do is provide them with the invite code to your class. We’re working on many more collaboration tools and will update you when they are implemented.

A second teacher added himself to my existing class, using activation code and then invitation code, but it cannot see students and their students works… this is very important, to have two teachers acting with full rights in the same class (or at least being able to see students works)